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<h2><span class="refentrytitle">Struct template pack_options</span></h2>
<p>boost::intrusive::pack_options</p>
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<h2 class="refsynopsisdiv-title">Synopsis</h2>
<div class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: &lt;<a class="link" href="../intrusive/reference.html#doxygen.pack__options_8hpp" title="Header &lt;boost/intrusive/pack_options.hpp&gt;">boost/intrusive/pack_options.hpp</a>&gt;

</span><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> DefaultOptions<span class="special">,</span> <span class="keyword">class</span> <span class="special">...</span> Options<span class="special">&gt;</span> 
<span class="keyword">struct</span> <a class="link" href="structboost_1_1intrusive_1_1pack__options.html" title="Struct template pack_options">pack_options</a> <span class="special">{</span>
  <span class="comment">// types</span>
  <span class="keyword">typedef</span> <span class="identifier">unspecified_type</span> <a name="doxygen.structboost_1_1intrusive_1_1pack__options_1ac519c646024ac0a2bed60806a86db4da"></a><span class="identifier">type</span><span class="special">;</span>
<span class="special">}</span><span class="special">;</span></pre></div>
<div class="refsect1">
<a name="id-1.3.17.42.22.4.4"></a><h2>Description</h2>
<p>This class is a utility that takes:</p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem"><p>a default options class defining initial static constant and typedefs</p></li>
<li class="listitem"><p>several options defined with BOOST_INTRUSIVE_OPTION_CONSTANT and BOOST_INTRUSIVE_OPTION_TYPE</p></li>
</ul></div>
<p>
</p>
<p>and packs them together in a new type that defines all options as member typedefs or static constant values. Given options of form:</p>
<pre class="programlisting"><span class="identifier">BOOST_INTRUSIVE_OPTION_TYPE</span><span class="special">(</span><span class="identifier">my_pointer</span><span class="special">,</span> <span class="identifier">VoidPointer</span><span class="special">,</span> <span class="identifier">VoidPointer</span><span class="special">,</span> <span class="identifier">my_pointer_type</span><span class="special">)</span>
<span class="identifier">BOOST_INTRUSIVE_OPTION_CONSTANT</span><span class="special">(</span><span class="identifier">incremental</span><span class="special">,</span> <span class="keyword">bool</span><span class="special">,</span> <span class="identifier">Enabled</span><span class="special">,</span> <span class="identifier">is_incremental</span><span class="special">)</span>
</pre>
<p>the following expression</p>
<pre class="programlisting"><span class="keyword">struct</span> <span class="identifier">default_options</span>
<span class="special">{</span>
  <span class="keyword">typedef</span> <span class="keyword">long</span>      <span class="identifier">int_type</span><span class="special">;</span>
  <span class="keyword">static</span> <span class="keyword">const</span> <span class="keyword">int</span>  <span class="identifier">int_constant</span> <span class="special">=</span> <span class="special">-</span><span class="number">1</span><span class="special">;</span>
<span class="special">}</span><span class="special">;</span>

<span class="identifier">pack_options</span><span class="special">&lt;</span> <span class="identifier">default_options</span><span class="special">,</span> <span class="identifier">my_pointer</span><span class="special">&lt;</span><span class="keyword">void</span><span class="special">*</span><span class="special">&gt;</span><span class="special">,</span> <span class="identifier">incremental</span><span class="special">&lt;</span><span class="keyword">true</span><span class="special">&gt;</span> <span class="special">&gt;</span><span class="special">::</span><span class="identifier">type</span>
</pre>
<p>will create a type that will contain the following typedefs/constants</p>
<pre class="programlisting"><span class="keyword">struct</span> <span class="identifier">unspecified_type</span>
<span class="special">{</span>
   <span class="comment">//Default options</span>
   <span class="keyword">typedef</span> <span class="keyword">long</span>      <span class="identifier">int_type</span><span class="special">;</span>
   <span class="keyword">static</span> <span class="keyword">const</span> <span class="keyword">int</span>  <span class="identifier">int_constant</span>  <span class="special">=</span> <span class="special">-</span><span class="number">1</span><span class="special">;</span>

   <span class="comment">//Packed options (will ovewrite any default option)</span>
   <span class="keyword">typedef</span> <span class="keyword">void</span><span class="special">*</span>     <span class="identifier">my_pointer_type</span><span class="special">;</span>
   <span class="keyword">static</span> <span class="keyword">const</span> <span class="keyword">bool</span> <span class="identifier">is_incremental</span> <span class="special">=</span> <span class="keyword">true</span><span class="special">;</span>
<span class="special">}</span><span class="special">;</span>
</pre>
<p>If an option is specified in the default options argument and later redefined as an option, the last definition will prevail. </p>
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<div class="copyright-footer">Copyright © 2005 Olaf Krzikalla<br>Copyright © 2006-2015 Ion Gaztanaga<p>
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